The present invention relates to a machine for the treatment of containers provided with a neck, such as bottles, flasks or the like.
The present invention relates more particularly to a machine for the treatment of containers of the abovementioned type by the depositing of a barrier-forming internal coating by means of a microwave plasma, especially for the purpose of allowing the packaging of oxidation-sensitive liquids in the containers, said machine comprising at least one treatment station for a container provided with a neck, each treatment station comprising a nipple which comprises gripping means for seizing the container externally by its neck and means for connecting the interior of the container to a vacuum-pumping circuit in a leaktight manner, said machine being of the type in which the nipple is mounted slideably along a substantially vertical axis with respect to a treatment enclosure between an axial transfer position and an axial treatment position, so as to allow the axial insertion of the container into the enclosure via a corresponding aperture, the nipple comprising an annular closing portion which comes to bear axially against a corresponding portion of the enclosure in a leaktight manner in order to close said aperture of the latter, said machine being of the type in which the gripping means comprise a tubular supporting cuff which is coaxial with respect to the neck of the container and is fixed in relation to the nipple and which is provided with a series of open-ended radial drillholes, each intended for receiving a ball movable radially between an inner gripping position, in which the ball cooperates with the neck in order to seize the container, and an outer release position.
In this type of machine, the container is generally arranged right way up, that is to say with the neck directed upward, the nipple sliding axially from the top downward in order to seize the container, during a gripping phase, and to bring it into the enclosure and from the bottom upward in order to remove the container and to release it, during a release phase.
The balls mounted in the nipple are stressed radially against the neck of the container by means of an O-ring made from elastic material.
With a nipple equipped with such a type of gripping means, the gripping of the container takes place by force fitting in the following way. During the gripping phase, the nipple exerts an axial force on the container from the top downward, in order to repel the balls radially outward, counter to the elastic return force applied to the balls by the O-ring, so as to allow the insertion of the neck of the container into the nipple.
The container is then seized by its neck by means of the balls which exert a radial bearing force against the neck under the stress of the O-ring.
Similarly, the release of the container takes place by force unfitting. During the release phase, the container is retained axially downward by an element which comes to bear axially against a shoulder of the container, so as to repel the balls outward and so as to allow the axial withdrawal of the nipple upward in relation to the container, counter to the elastic return force applied to the balls by the O-ring.
This type of gripping means has disadvantages since it generates relatively high forces on the container during the gripping phase and during the release phase.
Moreover, when the container is seized by the neck, the balls apply a radial bearing force to the convex axial wall of the neck, and this may damage the neck.
The present invention is aimed particularly at overcoming these disadvantages.